NTI INSTALLATION MANUALS

Part 7 - Connecting Electrical Service

3. Room Thermostat Wiring Connections To connect a room thermostat: 1. Access the low voltage wiring connections by following the directions in Item 2, Low Voltage Wiring Connections. 2. Loosen the cable clamp using a screwdriver and insert the wires leading from the room thermostat. 3. Connect the room thermostat wires to the terminals indicated in Table 19 and Figure 51. 4. Ensure that the wires are well connected and not subject to stress when the control panel or cabinet cover are closed. CAUTION NOTE: Some newer thermostat models may draw too much power from the boiler and will require an additional power supply to operate properly. Review the instructions provided with the thermostat to determine if an additional power supply is needed. Failure to do so could result in improper boiler and/or thermostat operation.

7. Open the control panel cover to have access to the main PCB. See Figure 50.

Figure 50 - Access to Low Voltage Wiring Connections

Low Voltage Wiring Connections

4. Outdoor Sensor Connections

Remote Control Connection

BUS

NOTE: WHEN CONNECTING THE BOILER TO EXTERNAL CONTROLS, DO NOT RUN 120V CABLES AND CABLES FOR CONTROL CIRCUITS (WHICH ARE LOW VOLTAGE) TOGETHER. USE SEPARATE CABLES TO PREVENT INDUCED VOLTAGE ON THE LOW VOLTAGE CIRCUITS.

Room Thermostat 2

TT2

Outdoor Sensor

OD

Tank Temperature Sensor (Probe / Aquastat)

TNK

System Sensor (Cascade Manager)

SYS

Outdoor Sensor

Room Thermostat 1

TT1

Table 19 - Low Voltage Wiring Connections

Remote Control (optional)

Outdoor Sensor

Tank temp. probe

System Sensor

OK

Room Thermostat

1

2

3

4

5

6

7

Connector OD on PCB

Figure 52 - Outdoor Sensor Connection

5. Aquastat (Default) and Tank Sensor (Optional) Connections (non-Combi Models) The boiler is designed for managing the production of domestic hot water via an indirect water heater (IWH) in one of two ways: i. AQUASTAT (default) - with parameter 228 = 2, the tank temperature is managed through an ON/OFF aquastat installed in the tank. When an aquastat is equipped, the boiler target temperature for DHW IWH demands can be adjusted via parameter 2.10.1 - default setting is 179 o F. ii. TANK SENSOR (optional) - with parameter 228 = 1, the boiler manages the IWH temperature directly via an NTC sensor installed in the tank and connected to the boiler (see electrical diagram). The setting of the tank temperature is done through the “+” and “-” buttons on the left side of the display. When a tank sensor is equipped, the boiler target temperature for DHW IWH demands can be adjusted via parameter 2.10.1 - default setting is 179 o F.

BUS T B 120V

5V IN TT2 OD TNK SYS TT1 120V 120V 120V 120V 120V

CN1

Figure 51 - Low Voltage Wiring Connections

CAUTION DO NOT CONNECT 120V TO ANY CONTROL WIRING CONNECTION! DOING SO WILL RESULT IN IMPROPER OPERATION AND POSSIBLE DAMAGE TO THE BOILER. SUCH DAMAGES ARE NOT COVERED BY PRODUCT WARRANTY!

Remove the factory installed jumper from TT1. NOTICE

50